The present invention relates to a drip cleaning attachment for attachment to a vacuum cleaner, suction cleaner, or the like, wherein liquid, and particularly water or water mixed with a cleaning concentrate, such as a detergent, is dispensed to a surface to be cleaned, such as a carpet, floor, upholstery, or the like, and then the liquid, any dirt dissolved in the liquid and dirt on the surface are suctioned from the surface.
Various drip cleaning attachments to a vacuum cleaner intake hose are background to this invention. For example, see U.S. application Ser. No. 282,103, filed Dec. 9, 1988 and see U.S. application Ser. No. 358,248, filed May 26, 1989. These drip attachments to a vacuum cleaner hose share a number of characteristics. There is a common housing for the drip unit and for the suction inlet. That common housing is attached to a wand that is in turn attached to the inlet end of a conventional suction hose leading to the vacuum cleaner. The liquid drip dispenser is positioned in the common housing adjacent to the suction nozzle and usually a short distance behind the suction inlet, so that they are near enough to make the entire housing somewhat compact in shape for appearance and function purposes. The width of the drip outlet from the drip dispenser is substantially the same as the width of the suction inlet, as they are in the same housing.
The liquid and the cleaning concentrate to be dispensed by the drip unit may be supplied from various sources. Supply of liquid from a stationary water supply, like a faucet, through a hose to the drip unit is shown in U.S. application Ser. No. 358,248, filed May 6, 1989. Supply of cleaning liquid from a tank mounted on the wand or on the drip attachment is shown in U.S. application Ser. No. 282,103, filed Dec. 9, 1988. The drip attachment includes appropriate means for dispersing the liquid supply over the entire width of the drip outlet. See e.g. the cascade or waterfall in U.S. application Ser. No. 282,103.
The present invention is concerned with the supply of cleaning concentrate, such as detergent, soap, floor cleaner, carpet shampoo, upholstery shampoo, or the like, to the surface to be cleaned. It is known to supply a preformed mixture of water or cleaning solution and cleaning concentrate in a desired mixture ratio and to drip that onto the surface, as from a supply tank. Providing a tank of liquid, like mixed liquid and cleaning concentrate, in a tank on the wand has the obvious limitation that the supply cannot be so large as to make the attachment very heavy. Therefore, the liquid supply will likely be exhausted after a short time and must be replenished frequently, causing possible user inconvenience.
An alternative is to connect a conventional water supply, e.g. from a faucet or tap, through a unit which dispenses detergent, shown, for example in U.S. application Ser. No. 358,248, and the flowing water supply picks up detergent from the detergent supply, and this mixture is then dripped through the unit.
If the liquid is supplied from a remote liquid source, like a faucet or even a supply tank, and if the liquid from the source is to pick up cleaning concentrate in its flow path, there is sometimes a problem of adjusting the ratio between the liquid and the cleaning concentrate so as to obtain the desired cleaning without wasting concentrate or providing too much concentrate. Systems which mix water and cleaning concentrate shortly before dispensing can be complicated and unreliable, and unless the system is constantly observed, the desired ratio of liquid to concentrate mix is not obtained.
There can be a serious problem if the liquid cleaning concentrate backs up into the water supply due to a negative pressure condition such as, a back flow that may occur when the water supply is shut off. In some countries and in some municipalities, no attachment may be made to a water supply which adds chemicals to the outflowing water from the supply unless there is a sufficient spacing between the water supply and the cleaning concentrate to prevent contamination due to back flow.
Where liquid cleaning concentrate is used, there are dangers of spillage, leakage, possible freezing and other liquid handling and storage problems. Finally, wherever liquid concentrate is mixed with a supply of flowing liquid and then they move together through a tube or pipe, the pipe is filled with the cleaning concentrate. In order to prevent contamination and to ensure proper system performance, the tubing, conduits, valves, etc. for the concentrate and for the mixture of cleaning concentrate and liquid must be cleaned and flushed, requiring extra work for the user.